Which of the following activities might indicate a potential insider threat?

Logging onto a system during unusual hours can be a significant indicator of a potential insider threat for several reasons. This behavior is atypical for most employees who generally adhere to regular working hours. When individuals access systems at unusual times, it can suggest they are trying to bypass normal monitoring processes or are engaging in activities that they do not want to be seen by others. Unusual hours can also indicate illicit actions, such as data exfiltration or unauthorized access to sensitive information, which might be part of malicious insider activities.

In contrast, using work email for personal messages could display a lack of professionalism or breach of company policy, but it isn't inherently a sign of malicious intent. Similarly, attending team meetings and submitting regular reports are standard practices expected of employees and do not indicate any threat or suspicious behavior. Hence, the focus on logging into a system at strange hours is vital in identifying and mitigating potential insider threats.